Scoliosis

Have you ever admired a ballerina's perfectly arched body? Her graceful maneuvers exaggerate the spine's natural curve. Sometimes, however, the spine bends from side to side in an unnatural "S" shape called scoliosis.

Just 2 to 3 percent of us have scoliosis, says the National Scoliosis Foundation. Still, scoliosis worries parents because it can severely affect children. Experts aren't sure what causes most scoliosis, but if anyone in your family has it, your child has a 20 percent chance of developing it.

Scoliosis usually appears during pre-adolescence or adolescence, and is up to eight times more likely in girls than boys. Experts say it may have something to do with the major growth spurt that occurs during this period.

A three-year span in puberty worries doctors most, since the curve can worsen up to 25 degrees a year. As growth ends, scoliosis stops worsening.

Scoliosis can't be cured, but early diagnosis allows control:

With a stable curve of 20 degrees or less, the doctor will generally monitor the child with periodic X-rays.

A curve of 25 degrees or more in a child entering a growth spurt may pose a high risk for worsening. Doctors often prescribe a plastic brace, worn up to 22 hours a day for up to five years.

For a curve of more than 40 degrees in the lower back or more than 45 degrees in the upper back, the doctor may recommend surgery.

Red flags

Ask your child to bend forward from her waist, keeping her hands together.

If one side of her back is higher than the other, that could suggest scoliosis, experts say.